BMI-1 SiRNA Suppressed Proliferation?Metastasis And EMT By Blocking MD-2/TLR4/MyD88 Complex-mediated NF-?B Signaling

AIMS:lipopolysaccharide(LPS)from bacterium promote metastasis and Epithelial-mesenchymal transition(EMT)in colorectal cancer cells through stimulating myeloid differentiation protein-2(MD-2)/Toll-like receptor 4(TLR4)/myeloiddifferentiationfactor88(MyD88)complex-mediated nuclear factor kappa B(NF-?B)signaling.Our study aimed to evaluate the relationship between BMI-1 and MD-2/TLR4/MyD88 complex-mediated NF-?B signaling on colorectal cancer development.METHODS:The expression of IL-6,L-1?,TNF-?mRNA and proterin in colorectal cancer cells was detected using RT-PCR and ELISA.The expression of BMI-1,MD2,TLR4,MyD88 mRNA and proterin in colorectal cancer cells was detected using RT-PCR and Western blot.The expression of p-NF-?B p65,NF-?B p65,I?B?and vimentin,N-cadherin,E-cadherin in colorectal cancer cells was detected using Western blot.Transwell assays and MTT assay were used to evaluate the proliferation,migration and invasion in colorectal cancer cells.Chemically synthesized siRNA targeting the BMI1 gene(BMI-1 siRNA)was transiently transfected into colorectal cancer cells to silence BMI-1.THP-1-CM was collected from the THP-1 medium,which were treated with LPS,to simulate inflammation on internal environment induced by LPS.RESULT: THP-1-CM observably promoted genetic expression of IL-6,IL-1?,TNF-?in colorectal cancer cells HT-29.THP-1-CM accelerated the protein synthesis of BMI-1,MD2,TLR4,MyD88,vimentin,N-cadherin,E-cadherin and phosphorylation of NF-?B and tumor cells' metastasis and EMT without proliferation.The impacts BMI-1 siRNA in colorectal cancer cells treated by THP-1-CM were as follows: inhibiting the protein synthesis of BMI-1,MD2,TLR4,MyD88,vimentin,N-cadherin,E-cadherin and phosphorylation of NF-?B;inhibiting tumor cells' metastasis and EMT without proliferation.CONCLUSION:THP-1-CM promotes the expression of BMI-1,IL-6,IL-1?,TNF-?result to metastasis and EMT in colorectal cancer cells by activating MD-2/TLR4/MyD88 complex-mediated NF-?B signaling.BMI-1 siRNA suppresses colorectal cancer cells ' metastasis and EMT induced by LPS by blocking MD-2/TLR4/MyD88 complex-mediated NF-?B signaling,suggesting that BMI-1 may be a potential therapeutic target for the treatment of colorectal cancer.